Valve train devices are known that have a mechanism for switching over the lift of gas-exchange valves. Gas-exchange valves, especially the inlet and outlet valves of an internal combustion engine, can be actuated directly or indirectly by means of a camshaft. In order to switch over the valve lift, cams that are adjacent on the camshaft are provided with different cam shapes and are combined to form a cam unit. Due to an axial movement of the cam units on the camshaft, the lift of the gas-exchange valves is changed as a function of the cam contours. In order to move the cam units, an adjustment shaft is provided that runs parallel to the camshaft and that has corresponding elements for engagement with the axially movable components such as, for example, cam units. The adjustment shaft is rotatably mounted parallel to the camshaft in several shaft bearings in a housing. The housing can be a cylinder head, a ladder chassis, modules or other means for accommodating an adjustment shaft. At least one adjustment mechanism is mounted on the adjustment shaft and it is associated with a cam unit in order to directly or indirectly actuate gas-exchange valves.
German patent publication DE 10 2008 061 440 B3 describes a rotatable adjustment shaft which is arranged parallel to a camshaft and on which two adjustment means as well as between the adjustment means two catches are arranged in a torque-proof manner, whereby they can be moved axially on the adjustment shaft in order to switch over the valve between two different cam profiles of a cam package that can be moved axially on the camshaft. When the adjustment shaft is rotated, the catches are moved axially on the adjustment shaft, whereby the rotation is effectuated by the camshaft. For this purpose, there is a torque-proof but axially movable gear wheel that is arranged on the adjustment shaft, that serves to rotate the adjustment shaft, and that, by means of a drive arranged on the adjustment shaft, is made to engage with a tooth segment arranged on the camshaft.
German preliminary published application DE 10 2009 057 691 A1 discloses an adjustment shaft that is arranged parallel to a camshaft and that can be connected to the camshaft by means of an actuating gear, so that, when an effective engagement with the camshaft is established, the adjustment shaft is rotated by the camshaft, as a result of which a cam package provided with different cam profiles is moved axially on the camshaft by means of catches and a shift gate. The actuating gear according to the invention for connecting the camshaft to and disconnecting the camshaft from the adjustment shaft consists of a one-arm or multi-arm lever system and of a profiled gate part. The lever system is arranged securely on the adjustment shaft. The gate part is arranged so as to be torque-proof but axially movable on the camshaft, whereby it can be selectively engaged with and disengaged from the lever system by means of an actuator.
German preliminary published application DE 10 2011 115 788 A1 discloses an adjustment shaft actuator comprising a cam unit that has a cam and that is mounted on a camshaft in a torque-proof manner, and also comprising a lever unit that is mounted on an adjustment shaft in a torque-proof manner and that is in the form of a pivoted lever with a first lever arm and with an additional lever arm that is axially at a distance and angularly offset. As a function of the position of the cam unit and of the lever unit relative to each other, one of the lever arms is operatively connected to the cam, whereby, owing to the rotational movement of the camshaft, a pivoting movement is applied to the corresponding lever arm via the cam contour, and the adjustment shaft is rotated. Two rotational positions can be implemented by means of the adjustment shaft actuator.